Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked

Endpoint summary

Description of key information

Skin irriation (OECD 431 and 439): not irritating (BASF, 2012)
Eye irritation (OECD 437 and EpiOcular): not irritating (BASF, 2012)

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

Skin irritation:

In a GLP compliant in vitro EpiDerm™ test (BASF SE, 2012), according to OECD guidelines 431 and 439, the potential of Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked to cause dermal corrosion/irritation was assessed by a single topical application of the undiluted test substance (about 55 mg) to a reconstructed three dimensional human epidermis model. For the corrosion test two EpiDerm™ tissue samples were incubated with the test substance for 3 minutes and 1 hour, respectively. The irritation test was performed with three EpiDerm™ tissue samples, which were incubated with the test substance for 1 hour followed by a 42-hours post-incubation period. Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation using a colorimetric test. The reduction of mitochondrial dehydrogenase activity, measured by reduced formazan production after incubation with a tetrazolium salt (MTT) was chosen as endpoint. The formazan production of the test substance treated epidermal tissues is compared to that of negative control tissues. The quotient of the values indicates the relative tissue viability.

The test substance is not able to reduce MTT. In the corrosion test, the mean viability of the test-substance treated tissues determined after an exposure period of 3 minutes was 103%, and it was 93% after an exposure period of 1 hour. In the irritation test, the mean viability of the test-substance treated tissues determined after an exposure period of 1 hour with about 42 hours post-incubation was 94%. Based on the observed results and applying the evaluation criteria it was concluded, that Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked does not show a skin irritation potentialin the EpiDerm™ skin corrosion/irritation test under the test conditions chosen.

Eye irritation:

In a GLP compliant in vitro EpiOcular™ Eye irritation test (BASF SE, 2012), the potential of Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked to cause ocular irritation was assessed by a single topical application of about 55 mg undiluted test substance to a reconstructed three dimensional human cornea model. Two EpiOcular™ tissue samples were incubated with the test substance for 90 minutes followed by a 18-hours post-incubation period. Tissue destruction was determined by measuring the metabolic activity of the tissue after exposure/post-incubation using a colorimetric test. The reduction of mitochondrial dehydrogenase activity, measured by reduced formazan production after incubation with a tetrazolium salt (MTT) was chosen as endpoint. The formazan production of the test substance treated epidermal tissues is compared to that of negative control tissues. The quotient of the values indicates the relative tissue viability. The test substance is not able to reduce MTT directly. The mean viability of the test-substance treated tissues was 112%. Based on the observed results and applying the evaluation criteria it was concluded, that Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked does not show an eye irritation potential in the EpiOcular™ eye irritation test under the test conditions chosen.

In a GLP compliant in vitro Bovine Corneal Opacity and Permeability Test (BCOP Test) (BASF SE, 2012) according to OECD guideline 437, the potential of Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked to cause serious damage to the eyes was assessed by a single topical application of 750 μL of the undiluted test substance to the epithelial surface of isolated bovine corneas. Because the test substance could not be prepared as a 20% preparation in de-ionized water, it was applied undiluted. For better handling it was heated at ca. 70 degrees centigrade and discs of the test substance were formed according to the size of the cornea. Before application the discs were cooled down to room temperature. Three corneas were treated with the test substance for an exposure period of 4 hours. Corneal opacity was measured quantitatively as the amount of light transmission through the cornea. Permeability was measured quantitatively as the amount of sodium fluorescein dye that passes across the full thickness of the cornea. Both measurements were used to calculate an In Vitro Irritancy Score of the test substance relative to the control corneas.

The BCOP test showed the following results for the test substance a Mean Opacity Value of -4.5; a Mean Permeability Value of 0.000; and an In Vitro Irritancy Score of -4.5. For the negative control the values were respectively 8.2; -0.001 and 8.2 and for the positive control 73.0; 3.613 and 127.2, respectively. The mean opacity value of the NC is out of the historical range, because the values of two corneas are too high. However, as all other acceptance criteria were met in the test and due to the unambiguous results of the test substance, the evaluation of the study is not expected to be influenced by this deviation. Based on the observed results and applying the evaluation criteria it was concluded, that Hexane, 1,6-diisocyanato, homopolymer, N-butyl-1-butanamine-blocked does not cause serious eye damage in the Bovine Corneal Opacity and Permeability Test (BCOP Test) under the test conditions chosen.

The test method according to the regulatory accepted protocol at the time of reporting does not allow for the evaluation of eye irritation. The result does not exclude an irritation potential of the test substance. For final assignment of a risk phrase at present, results from another study would be needed.

Justification for classification or non-classification

Based on the available data, the test substance is not classified with regard to skin and eye irritation/corrosion according to Directive 67/548/EEC (DSD) and Regulation (EC) No 1272/2008 (CLP), respectively.